Re: Integration in ferret

[Steve Hankin <hankin@xxxxxxxxxxxxx>]

Hi Bernadette,

The general approach to integrating over irregular limits is to use a mask as
follows.

LET MY_Z_UPPER_LIMITS = some-function-of-Y, only
LET MASKED_U = IF Z[g=my_var] LT MY_Z_UPPER_LIMITS THEN U

The omited ELSE clause means that points whose Z coordinate exceeds
MY_Z_UPPER_L:IMIT are masked out.

Now you simple integrate using

    MASKED_U[Z=0:`max`@DIN]   where `max` is the full Z range

Notes:

   * You can omit the "0:`max` if the Z limits are undefined -- it will
     default to integrating over the full (masked) region
   * Using "... ELSE 0" in the definition of MASKED_U would be equivalent for
     purposes of integrations ... though clearly not so for averaging.

    - steve

====================================================

Bernadette Fritzsch wrote:

> Hi,
>
> i have a dataset with a 2D array u(y,z) and i want to plot a new data
> which is defined :
>
> new(y,z) = Integral of u(y,z') dz' with z'=0...z
>
> i tried it with the @DIN transformation:
> let new = u[z=1:k@DIN]
>
> but because of the variing limits in z it does not work. Trying to use
> some masking for the data failed for the same reason of the variing limits
> for integration.
>
> Anyone can help me?
>
> Thanks!
>
>         Bernadette

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